Induction heating apparatus



March 25, 1958 w. A. EMERSON INDUCTION HEATING APPARATUS 2 Sheets-Sheet 1 Filed 001;. 28, 1954 Fig.1.

IIIIII IIIIIIIIIIIIII INVENTOR Williom A.Emerson BY ATTORNEY W. A. EMERSON INDUCTION HEATING APPARATUS March 25, 1958 2 Sheets-Sheet 2 Filed Oct. 28, 1954 United States Patent INDUCTIGN HEATING APPARATUS William A. Emerson, Austin, Tex., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application October 28, 1954, Serial No. 465,163 4 Claims. (Cl. 21910.43)

This invention relates to apparatus for the heat treatment of metallic workpieces and, more particularly, to an inductor member for such heat treatment.

It is an object of the present invention to provide an improved inductor member.

It is another object of the invention to provide an improved heat treating member which will produce a more uniform heat treatment pattern at a higher efliciency than prior art apparatus.

It is a further object to provide an improved inductor member including an iron core adapted for use with either low or high frequency heat treating energy.

It is an additional object to facilitate the handling of workpieces to be heat treated by moving only a portion of the inductor member, which portion is relatively light in weight and comparatively simple to move relative to the workpiece surface to be heat treated.

It is a different object to provide an inductor member which can be made to closer tolerances with less effort and cost involved and, accordingly, will produce an improvide heat treatment operation.

In accordance with the invention, an iron core inductor member is provided for the heat treatment of selective services of workpieces. Such selective services may, in particular, be valve seats in automobile engine blocks, but may be other suitable types of workpieces. The inductor member comprises a single or multiple turn inductor coil which is placed in an annular channel recess in a cooperative core member made of magnetically permeable material such as powdered iron. The annular recess is so constructed that the core may be moved relative to the inductor coil such that the inductor coil can be fixedly positioned relative to the workpiece surface, and the core only need be raised to allow the movement of the workpiece surface in a direction perpendicular to the axis of the coil and relative to the inductor coil. This facilitates the work handling in that no cumbersome electrical connections are required since the coilneed not be moved away from the work surface to clear the work surface for movement from said heat treatment position.

These and other objects of the invention are effected as will be apparent from the following description taken in accordance with the accompanying drawing, which forms a part of this application and in which:

Figure 1 is an illustrative side view of apparatus in accordance with the present invention showing suitable inductor members for heat treating four valve seats in an automobile engine block or like workpiece;

Fig. 2 is a top view of a single turn inductor member in accordance with the present invention;

Fig. 3 is a side section view of the apparatus shown in Fig. 2; l Fig/41s a top view of an inductor member including a multiple turn inductor and core; 7

Fig. is a side section view of the apparatus shown in Fig. 4;

Figs. 6 and 7 show a modified multiple turn inductor and core; and

Fig. 8 shows a still diiferent inductor member and core.

In Fig. 1, there is shown a common power supply 10 connected to supply suitable frequency energy to a plurality of work stations 12, 14, 16, and 18. At each of these latter work stations there is provided an inductor member including a core 26 and an inductor coil 22. The inductor coil 22 can be seen only in work stations 12 and 14 in that the core 2 3 at the work stations 12 and 14 has been raised to clear the valve seats to be heat treated in the engine block workpiece 24. At work stations 16 and 18, the cores 20 are in position for the heat treatment of valve seats in the engine block workpiece 24. The workpieces are supported by means of a movable work support member 26, which may be in the form of an endless conveyor-like workpiece moving apparatus.

In Fig. 3, there is shown a side section view of an inductor member suitable for use at any of the work stations 12, 14, 16, or 18 in Fig. 1. The inductor coil 22, shown in Fig. 3, comprises a single turn inductor member and is composed of a single turn of preferably round copper tubing, said turn having a diameter such as to set directly over the valve seat 28 in the engine block workpiece 2d. The energy supply leads for the inductor coil 22 are arranged substantially parallel relative to the axis of the inductor coil 22. and project from the inductor coil 22 up through the core 26 such that the core 20 may be moved relative to the inductor coil 22 a sufiicient amount to allow the workpiece 24 to be moved in a direction substantially perpendicular to the axis of the inductor coil 22 to remove the valve eat work surface 23 to be heated away from the respective work station or heat treatment position when the heat treatment is completed. The supply leads 30 and 32 for the inductor coil 22 are provided with'a minimum spacing therebetween in an eifort to produce the non-uniform heating efiect of the valve seat 28 at a position corresponding to the position where the leads 30 and 32 are connected to the inductor coil 22. The powdered iron core 29 is formed to substantially surround the inductor coil 22 on three sides of the individual turn, and is open at the fourth side, said opening being provided to allow the core 20 to be moved relative to the inductor coil 22 in a direction substantially parallel to the axis of the inductor coil 22. Since the core 20 surrounds the inductor coil 22 on substantially three sides thereof, it is open at the valve seat. This arrangement allows for a rather low reluctance path around the coil 22 with a resultant increase in efficiency of heating over an air cored coil. Because the coil 22 is pulled back into the core 2t) somewhat, the flux has a iittle area in the core 20 where it may even out before cutting the valve seat. This evening out of the fin); due to the core 20, as well as the rather long heat time required, cause this coil to give a very uniform heat pattern over the entire seat. A support 34 is provided for the core 29, which support 34 is operative to move the core 29 relative to the inductor coil 22.

In Fig. 2, there is shown a top view of the apparatus shown in Fig. 3, with the position of the inductor coil 22 relative to the core 20 more clearly illustrated, and the position of the core support 34 shown such that the core may be moved without disturbing the inductor coil 22.

In Fig. 5, there is shown a side section view of a multiple turn inductor coil 36 and a surrounding core 20, with the surrounding core being provided with an annular channel or recess 38, wherein the turns of the inductor coil 36 may be positioned. When a multiple turn inductor coil 36 is used with the core 20, the latter core 26 may preferably be formed with an interior removable portion so which may be removed to facilitate the positioning of the inductor coil 36. The removable core portion 4-0 is formed such that the core 20, including the interior portion 49, may be moved relative to the inductor coil 36 by means of a core support member 34.

In. Fig. 4 is shown a top view of the apparatus shown in Fig. 5, and more clearly illustrates the relative positions of the core 21) and the multiple turn coil 36 with the energy supply leads 42 and 44 shown. The core support member 34 is displaced a short distance from the axis of the core member 20 in that the supply leads %4 for the multiple turn inductor coil 36 are positioned substantially at the axis of the coil 36.

Figs. 6 and 7 show a modified multiple turn inductor and core, with the core i being movable relative to the coil 52. The core 58 has an axial slot or opening 54 corresponding to the central axial energy supply lead 55, which opening 54 allows the core 59 to be moved axially relative to the coil 52.

Fig. 8 shows a still difierent coil and core arrangement, with the core 53 not being movable relative to the coil 60.

In the operation of the apparatus shown in Fig. l, the workpiece 24 is moved into position with the work surfaces to be heat treated corresponding in position to the respective work stations 12, 14, 16 and 18. The cores 20 are then lowered relative to the inductor coils 22 either sequentially, altogether or singly as may be desired, and the energy from the power supply source is applied to the work surface to be heat treated when the cores 29 are in position relative to the inductor coils 22, as best shown in Fig. 3 and Fig. 5, depending upon the type of inductor coil which is employed. In this respect, the multiple turn coil 36 can be considered to be the operative equivalent of the single turn coil 22, and hereafter the single turn coil 22 will be specifically described. However, the multiple turn coil 36 may, in some applications, be preferable for use with lower frequency energy. After the desired period of heat treatment, the cores are raised relative to the inductor coils 22 such that the workpiece. 24 may be moved in a direction substantially perpendicular to the axis of the coils 22 and the movement of the cores 2% In this respect, the power supply 10 may be continuously applied, and the energization of the work surface determined by the position of the core 20, or the power supply may cyclically energize the inductor coils 22, by means of suitable switching apparatus (not shown), as may be desired.

The inductor member shown in Fig. 3 may be more suitable for use with radio frequency energy, in that less current is required and the non-uniform heating effect of it at the position where the supply leads 30 and 32 are connected in the inductor coil 20, is less important; Suitable insulation material of which many types are known in the art can be provided between the supply leads 3d and 32. No special insulation is necessary between the inductor member 22 and the core 20, in that the core 20 is preferably made of powdered iron or like material which does not require an insulator at the low voltages employed. The position of the inductor member within the annular channel or recess of the coil 2t) is effective to even out the flux pattern provided by the inductor coil 22 to further minimize the effect of the supply leads 39 and 32 at the position where they are connected to the inductor coil 22.

The multiple turn inductor member, as shown in Fig. 5, may be preferable for use with lower frequency energy',fsuch as audio frequency'energy which requires higher currents, and, accordingly, the supply leads 42 and 44 are arranged with overlap leads to further minimize the non-uniform heating effect of their respective connections to the inductor coil 36. In the inductor member of Fig. 5, one of the supply leads 44 is positioned axially relative to the inductor member 36, and the other lead 42 is substantially parallel to the first lead 44, but is connected to the coil at a maximum distance from the first lead 44. The annular recess 33 provided in the core 20 has a depth such that the coil 36 is positioned within the core with a portion of the annular recess not filled by the coil 36 to provide a short flux path distance within the core for any slight irregularities of the flux pattern to be evened out and minimized before the flux enters the valve seat surface 28 to be heat treated.

The inductor members shown in Figs. 3 and 5 have the unique advantage that with workpieces 24, which are particularly bulky and cumbersome, need not be raised relative to the inductor coils 22, nor, on the other hand, the inductor coils 22 need not be moved relative to the workpieces 24 which, in turn, would introduce cumbersome electrical problems. The core 20 has a comparatively small mass compared to the work member 24, and the core 20 is the only member which need tobe moved to allow replacing a given workpiece 24 with a succeeding workpiece.

The apparatus of Figs. 6 and 7 is operative similar to the apparatus shown in Figs. 4 and 5, in that the core 50 can be moved relative to the coil 52 to allow any desired movement of the workpiece perpendicular to the axis of the coil 52;

The apparatus of Fig. 8 is operative such that the coil 60 and core 58 are moved as a single unit to allow any desired movement of the workpiece perpendicular to the axis of the coil 60.

While the invention has been shown in particularly the preferred embodiments thereof, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various modifications and changes without departing from the spirit and scope thereof. For example, the inductormembers of the present invention may be used for the hardening or heat treatment of workpieces which may require a quench operation after the work surface has been heated. The quench medium for this purpose maybe applied from within the inductor member 22 by providing quench fluid openings in the inductor coil adjacent to the heated surface of the workpiece, as well known in the art. Or the quench medium can be passed through the core support member 34 and the quench medium applied to the heated surface of the workpiece before the core 20 is lifted, after the core is lifted or during the movement of the core. In addition, the core, with or without the coil, may be rotated or moved during the heat treatment relative to the heat treated work surface to furtherminmize any non-uniform unheating effects thereof.

It is afurther modification of the present invention that the core of particularly the multiple turn coil for use with lower frequency energy need not be moved relative to the coil, but instead, the coil and core together can be moved relative to the workpiece or the workpiece moved relative to the coil and core.

I claim as my invention: 7

1. In heat treating apparatus for heat treating a surface of a metallic workpiece, the combination of a magnetically permeable core and an inductor having an axis, said core having an end portion positioned adjacent to said surface of the workpiece, said end portion having an annular channeled section for containing said inductor therein, a support member for said workpiece having a planar surface, with said workpiece being movable in a direction substantially perpendicular to said axis and along said planar surface, said core member being movable along said axis relative to said inductor and said surface of the workpiece.

2. In heat treating apparatus for heat treating a surface of a metallic workpiece, the combination of a magnetically permeable core, an inductor having an axis, said core having an end portion positioned adjacent to said surface of the workpiece to be heat treated, said end portion being provided with an annular recessed channel section, with the inductor being positioned entirely within said channel section, a support member for said workpiece having a planar surface, with said workpieces being movable upon said planar surface, and support means for said core for moving said core member along said axis relative to said coil and said workpiece.

3. In combination, a magnetically permeable core member having a generally annular recessed channel in one face thereof and passages through the core member leading from said channel, said passages being substantially parallel to the central axis of said channel, a generally annular inductor positioned within said recessed channel, and electrical leads extending from said inductor through said passages whereby the core may slide on the leads from a position wherein the inductor is located within said channel to a position wherein the inductor is outside of said channel.

4. In combination, a magnetically permeable core member having a recessed channel in one face thereof and passages through the core member leading from said channel, an inductor positioned within said recessed channel, and electrical leads extending from said inductor through said passages whereby the core may slide on the leads from a position wherein the inductor is positioned within said channel to a position wherein the inductor is outside of said channel.

References Cited in the file of this patent UNITED STATES PATENTS 2,182,341 Hulster Dec. 5, 1939 2,238,082 Somes Apr. 15, 1941 2,543,551 Krug Feb. 27, 1951 2,599,086 Beckius et al. June 3, 1952 2,655,589 Sorensen Oct. 13, 1953 2,717,364 Hodgin et a1. Sept. 6, 1955 FOREIGN PATENTS 275,887 France Sept. 1, 1951 

